Fossil teeth flesh out ancient kids’ varied growth rates

X-ray technique sheds light on hominid development

AGING DOWN A Paranthropus robustus child, represented by this jaw and teeth, died at age 3.1, according to new evidence. The child was several months younger at death than previously estimated. P. robustus lived in what’s now South Africa between 2 million and 1.5 million years ago.

Tanya Smith

Kids who belonged to now-extinct species in the human evolutionary family grew at unexpected rates, unlike the growth of either present-day people or apes, a new study of their teeth finds. As a result, the researchers can now more accurately estimate ages at death for ancient hominid youngsters whose fossil teeth have been found.

Using X-ray technology to examine microscopic growth lines inside fossil teeth, a team led by Harvard University anthropologist Tanya Smith concludes that researchers can no longer use living apes as developmental yardsticks for ancient hominids. The timing of tooth formation and molar eruption, which denotes the speed of overall physical development, fluctuated from one now-extinct species to another, the researchers report February 18 in PLOS ONE.

“Great ape developmental standards do not necessarily yield accurate age of death estimates” for ancient hominid

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